Plastic egg cartons



Jan. 9, 1968 D. c. TRIMBLE PLASTIC EGG CARTONS 5 Sheets-Sheet 1 Filed Jan. 18, 1967 DAVID C. TRIMBLE awe wk Jain. '9, 1968 D. c. TRIMBLE 3362;606

PLAS TI 0 EGG CARTONS Filed Jan. 18, 1967 3 Sheet$-$heet 2 Jan. 9, 1968 D. c. TRIMBLE 3,362,606

PLASTIC EGG CARTONS Filed Jan. 18, 1967 5 Sheets-Sheet 5 DAVID C. TRIMBLE INVENTOR whim ATTORNEY United States Patent Office 3,362,6fi6 Patented Jan. 9, 1968 3,362,606 PLASTIC EGG 'CARTONS David C. Trirnhle, Yorklyn, Del assignor, by mesne assignments, to Hercules incorporated, a corporation of Delaware Filed Xi'an. 18, 1967, Ser. No. 626,741 12 Ciaiins. (Cl. 2292.5)

ABSTRACT OF THE DESCLOSURE The herein disclosed egg carton is thermoformed from a thin sheet of foamed plastic material and comprises a tray-like base member and a pair of hinged cover members adapted to be swung to a closed position overlying the base member. The base member is provided with a plurality of posts along its longitudinal center line in cluding one or more cover supporting posts in which the free edges of the cover members rest and one or more cover retaining posts having slots for frictionally receiving and thus holding the edges of the cover members.

This application is a continuation-in-part of my prior application Ser. No. 541,187, filed Apr. 8, 1966, which was abandoned upon the filing of this application.

The present invention relates to an egg carton and more particularly to an egg carton of thermoformed foamed plastic material.

The object of this invention is to provide in an egg carton, such as that which forms the subject matter of my copending United States patent application Ser. No. 541,188, filed Apr. 8, 1966, now Patent No. 3,307,765 means for accurately nesting the cartons a gauged amount whereby they may be mechanically de-nestcd, and which means also contributes to the transverse rigidity of the carton and further provides means for latching the cover members closed and for supporting the cover members so that, after the cartons are filled, a plurality of them can be stacked one on top of the other without damaging the contents.

The present invention resides essentially in the use of a combination of one or more cover-retaining posts and cover-supporting posts in which each of the cover-retaining posts are slotted to receive edges of the cover members to hold the same in the closed position and each of the cover-supporting posts present a cover-supporting surface on which the-cover members are adapted to rest on edge. Because of the heights of the posts, the material is draped during thermoforming of the carton between the posts so that in the mid-portion of the drape, the material is folded onto itself, thereby forming a thickened section which is accurately molded in the nesting direction to the desired nesting height.

With the above and other objects in view, a presently preferred embodiment of the invention is hereinafter described with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of an egg carton constructed in accordance with this invention with one of the cover members illustrated in phantom in the open position.

FIG. 2 is a fragmentary top plan view of the egg carton of FIG. 1.

FIG. 3 is a fragmentary transverse sectional view taken substantially on the line 33 of FIG. 2.

FIG. 4 is a fragmentary longitudinal sectional view taken substantially on the line 4-4 of FIG. 2.

FIG. 5 is a fragmentary transverse sectional View similar to FIG. 3, but on an enlarged scale and with the cover members closed.

FIG. 6 is a fragmentary perspective view similar to FIG. 1, but illustrating a modified egg carton.

FIG. 7 is a fragmentary sectional view similar to FIG. 3 but illustrating the modified egg carton of FIG. 6.

FIG. 8 is a fragmentary top plan view of the modified egg carton of FIG. 6.

With reference to the drawings, the present invention is illustrated as embodied in an egg carton thermoformed from a sheet of any suitable foamed plastic material, for example, polystyrene, polyethylene, polypropylene, copolymers of ethylene and propylene, and the like. The illustrated carton comprises an open-topped, traylike base member 1 and a pair of generally U-shaped cover members 2, each of which is hinged along one edge to an upper longitudinal edge of the base member 1 by a hinge 3 and is adapted to be swung between a closed position overlying the base member and an open position in which the open top of the base member is exposed. The hinge 3 may be of the type and may be formed in the manner disclosed and claimed in my copending United States patent application Ser. No. 541,189, filed Apr. 8, 1966.

The base member 1 includes a pair of opposed side walls 4 and a pair of opposed end walls 5, which are discontinuous as noted below and which are tapered outwardly or diverge in the direction away from the bottom plane 6 of the base member 1 at angles of approximately sixty degrees to the plane 6. The free or upper edges of the side walls 4 and end walls 5 define the open top of the base member 1, which open top constitutes what is herein termed the top surface 7 that, in the embodiment of the invention illustrated in FIGS. 1-5, is substantially planar and parallel to the bottom plane 6.

The illustrated carton is of the standard 2 X 6 type in which there are one dozen egg-receiving pockets 8 arranged in two rows of six pockets each. The means for dividing the base member 1 to provide the pockets 8 comprises a central longitudinal partition 9 disposed mid way between the side walls 4 and five transverse partitions 16, which partitions 9 and 10 intersect and thereby interrupt the end walls 5 and side walls 4, rendering the same discontinuous. The partitions 9 and 10 are inverted V-shaped, with upper edges 11 and 12, respectively, and side walls 13 and 14 that, like the side walls 4 and end walls 5 of the base member 1, are inclined at angles of about sixty degrees to the bottom plane 6 of the carton. The pockets 8 are thus each defined by four opposed side walls formed by the side walls 4, the side walls 13 of the partition 9, and a pair of side walls 14 of the partitions 10, except for the end pockets wherein the end wall 5 is used in lieu of one of the walls 14, all of which walls diverge upwardly from a substantially square bottom wall 15 disposed in the bottom plane 6 and which may be cushioned.

At the intersection of the longitudinal partition 9 with each of the transverse partitions 10, there is provided a post which is either a cover-supporting post 16 or a coverretaining post 17, there being in the illustrated embodiment of the invention an alternating arrangement of five posts 16 and 17, consisting of three cover-retaining posts 17 located one each at the center and the two outer positions and two cover-supporting posts 16 located one each at the two intermediate positions. Each of the posts 16 has a cover-supporting surface in the form of a flat upper surface or top 18 and depending walls 19. The tops 18 are in the top surface 7 of the base member 1 and are substantially square, with the corners thereof centered over the upper edges 11 and 12 of the partitions 9 and 10. The cover-retaining posts 17 have walls 29 that are also arranged in a pattern that is substantially square in transverse crosswsection, with the corners thereof disposed directly over the upper edges 11 and 12 of the partitions 9 and 10. The posts 17 rise above the top surface 7 of the base member 1 and are provided with slots 21 that extend inwardly from the upper or free end thereof to a point at least substantially level with, but preferably slightly below, the top surface 7 of the base member 1, the slots 21 being arranged longitudinally of the base member 1 and from corner-to-corner of the posts 17 or, in other Words, with the center line thereof in a plane that is normal to the top surface 7 and includes the upper edge 11 of the longitudinal partition 9. The posts 17 also include tops 22 that slope inwardly and downwardly toward the slots 21 from the outermost corners thereof for the purpose of directing the edges of the cover members 2 into the slots 21.

The walls 19 and 20, as well as corresponding walls 23 and 24 that are formed respectively between the walls 4 and 14 and between the walls 5 and the adjacent walls 4 and 13, serve as corner walls for the pockets 8 and act to confine the eggs more closely in the pockets and to provide resilience so that the walls 4, 5, 13 and 14 can be flexed outwardly to accommodate eggs of a size larger than that for which the pockets were primarily dimensioned and thus providing a single carton that is sufficiently versatile that it can be used with a number of different sizes of eggs. The corner walls 19, 20, 23 and 24 may be planar or may be slightly convex and are arranged at an angle of substantially seventy-five degrees to the bottom plane 6 of the base member 1.

Each of the cover members 2 is generally U-shaped in transverse cross-section and includes a top wall 25 and a depending skirt portion including a hinged side wall 26, a free side wall 27, and end walls 28 extending between the two side walls. The cover members 2 are formed integrally with the base member 1 and are hinged along the edge of the hinged side wall 26 to the upper or free edge of the side wall 14 by means of the hinge 3.

The cover members 2 are dimensioned such that when they are closed the free side walls 27 are substantially normal to the top surface 7 of the base member 1 and in opposed or substantially surface-to-surface abutting relation to each other, and the top plates 25 are substantially in spaced parallel relation to the bottom plane 6 of the base member 1. The closed position of the cover members 2 is as illustrated in FIG. 5, that is, with the edge portions of the side walls 27 inserted in the slots 21 of the posts 17 and the free edges thereof seated on the coversupporting surfaces 18 of the posts 16. At the same time, the thickness of that portion of each of the free side walls 27 that is received within the slots 21 is more than onehalf the width of the slots 21 so that the combined thickness of the wall portions in the slots is greater than the width of the slots, thus requiring that they be forced into the slots and insuring that they will be frictionally retained therein. In this manner, the posts 17 serve to hold the cover members 2 closed while the posts 16 support the wall 27 on edge. The Wall 27 in turn supports the top wall 25 of the cover members so that a quantity of the filled cartons can be stacked one on the other for purposes of storage or shipment.

For a more detailed description of the specific configuration and dimensions of the base member 1 and the cover members 2, and of the functions and advantages thereof, reference is made to my above noted co-pending application Serial No. 541,188, filed Apr. 8, 1966, now Patent No. 3,307,765.

In order to facilitate storage, handling and transportation of the cartons before they are filled, they must be so made that they can be stacked or nested in a minimum of space and they must be sufiiciently uniform in stack height, which is herein used to designate the distance in the stacking direction from one point on one carton to the corresponding point of the adjacent cartons in the stack, so that they can be readily denested mechanically by commercial equipment. To adapt the cartons for de-nesting by existing equipment, the base member 1 is provided with a flange 29 in the top surface 7 and at the longitudinal center line of the base member 1.

In nesting the cartons, the stack height is a function of the angles and the thicknesses of the walls, that is, as the angles of the Walls are made progressively more normal to the bottom plane 6, the thickness of the wall that can be accommodated within a given stack height is progressively reduced. Generally, the objective is to provide nesting of the cartons within one-quarter inch, which is the standard dimension that provides a sufficiently compact stack and which is also the dimension upon which commercial de-nesting machines are designed to operate. An acceptable combination of thicknesses and angles that will produce a sufficiently rigid carton with reasonable overall dimensions and with a onefourth inch stack height can be obtained by using a one-sixteenth inch polystyrene foam and forming the walls at angles of about sixty to seventy-five degrees to the bottom plane 6 as described above.

While the above construction will permit stacking of the cartons within one-quarter inch stack height, the diff!- culties in maintaining exact angles and wall thickness during thermoforming of plastic foam renders it ditlicult if not impossible from a practical stand-point to obtain a sufficiently accurate and uniform stack height to provide for mechanical de-nesting. In the present construction, this accuracy is obtained by providing a gauged thickened portion 34), FIG. 5, at the apex of the longitudinal partition 9 between the cover-retaining posts 17, the top of which section is the upper edge 11 of the partition and the bottom of which is the edge 31.

In particular, the portion 30 may be formed during the forming of the carton from the foam sheet by what is generally conventional vacuum forming equipment with a plug assist in which the molds are arranged horizontal with the female mold at the bottom and the male mold at the top. The sheet is clamped in a frame and heated to forming temperature, and then is initially partially engaged with the female mold, or, more particularly, by the tops of the mold sections for forming the internal surface of the posts 17. By providing a short pause or hesitation in the closing of molds after the mold sections that form the posts 17 are inserted into the plane of the sheet, the sheet will either through gravity or the initial application of the vacuum or pressure, be caused to drape or sag about a line between the posts 17 along the center line of the carton, that is, in the clearance above the posts 16. This draping of the sheet causes that portion thereof that is midway between the posts 17 to double over onto itself or fold together beneath what eventually becomes the upper edge 11 of the longitudinal partition 9 to form the thickened section 30. The side walls of the sheet, being in a plastic condition, bond or adhere to each other when they are brought into contact by the draping. The thickness of the section 3% as folded is greater than the desired stacking height so that when the molds are then closed and the full vacuum is applied, the upper and lower edges 11 and 31 of the thickened section 30 are formed by the mating surfaces of the mold halves to exactly the desired stack height, e.g., one-fourth of an inch, and at exactly a uniform distance from the flange 29.

When the formed sheet is sufiiciently cooled, it is removed from the mold and the carton is trimmed therefrom. When the cartons are then nested, the under edge 31 of the thickened section 30: of the carton rests upon the upper edge 11 of the thickened portion of the underlying carton, thus positioning the two cartons at exactly the desired stack height along their longitudinal center line. While the cartons are free to tilt laterally about the line defined by the edges of the thickened portions 30, the flanges 29 are also located along the longitudinal center line and thus will remain properly spaced.

After the cartons are filled, the cover members 2 are swung to the closed position, with the free edge portions of the side wall 27 thereof inserted into the slots 21 of the posts 17 and with the wall 27 supported on its edge on the cover-supporting surfaces 18 of the posts 16. Since the free side walls '27 of both of the cover members 2 have a combined thickness that is greater than the width of the slots, the walls must be forced into the slot and are thereby frictionally held therein. At the same time, with the walls 27 supported on edge on the posts 16 and arranged along the longitudinal center line of the carton, they provide significant support for the top, which permits stacking of the filled cartons for purposes of storage and shipment.

In FIGS. 6, 7 and 8 there is illustrated an egg carton in accordance with this invention and embodying various modifications. In FIGS. 6-8, the modified elements of the carton are designated by the same reference numerals as the corresponding parts of the carton of FIGS. 1-5, together with the reference letter a. All other parts of the carton of FIGS. 6-8 are the same as the corresponding parts of the carton of FIGS. 1-5 and insofar as they are referred to, are designated by the same reference numerals.

In the egg carton of FIGS. 6-8, there is a tray-like base member 1a and a pair of cover members 2a having free side walls 26 hinged along hinge lines 3 to the upper .or free edges of the longitudinal side walls 4 of the base member 1a. The base member 1a has a top surface 711 (FIG. 7) which, rather than being planar as is the top surface 7 of the embodiment of FIGS. 1-5, is curved or inclined downwardly from the free or upper edges of the side walls 4, that is, at the hinge lines 3, toward a low point at the longitudinal center line of the base member In.

Each of the end walls 5a of the base member 1a has an upper edge 32 that follows the inclined top surface 7a and is thus shorter at the center of the base member than the comparable edge of the wall 5 of the carton disclosed in FIGS. 1-5 by an amount equal to the spacing between the top surface 7a and the planar top surface7. The height of the free side walls 27a of the cover members 2a is increased over the dimension of the walls 27 in the carton of FIGS. 1-5 by the same amount so that the top walls 25 of the cover members 2a will be parallel to the bottom plane 6 of the base member 1a when the cover members are in their closed positions. By lowering the free edge of the wall 27a, the cover-retaining posts 17a can also be lowered by a corresponding amount without reducing the frictional engagement between the slot 21a and the edge portions of the walls 27a or, conversely, with posts 17a of the same height as the posts 17, the slots 21a can be made deeper and thus provide increased frictional engagement with the walls 27a.

Reducing the height of the posts 17a reduces the amount of drawing that is required during thermoforming of the carton which makes it easier to form the carton and also increases the thickness of the material in the jaw-like free end of the posts 17a and thus strengthens the posts outside the slots 21a so that they will maintain a firmer grip on the inserted edge portions of the free side walls 27a of the cover members 2a.

The frictional engagement between each of the coverretaining posts 17a with the portion of the free side walls 27a of the cover members inserted into the slot 21a, is also increased as in the capacity of the slot to receive side walls of varying thickness, by skewing the slot 21a relative to the center line of the carton, as can be seen in FIG. 8. As shown, the slot 21a is at a slight angle to the longitudinal center line of the carton, for example, at an angle of between five to ten degrees. Thus, when the edge portions of the free side walls 27a of the cover members 2a, which are parallel to the longitudinal center line of the carton, are inserted into a slot 21a, the walls 27a are engaged by the post with a maximum pressure on the walls 27:: at the corners of the slot 21 at the opposite ends thereof as the edge portions of the walls are forced to bend from the straight path to the inclined path of 6 the slot 21a. The frictional engagement between the post and the walls 27a is of course a function of the combined thickness of the walls relative to the width of the slot 21a, as well as the length of the slot 21a and the angle thereof relative to the center line of the carton. With a post 17a that tapers upwardly, the length of the slot 21a accordingly increases downwardly of the post as the thickness of the post increases so that the bend imposed upon the walls 27a and thus the frictional grip upon them increases as the walls 27a are inserted further into the the slots 21a. Preferably, the length, width and angle of the slot 21a is such relative to the thickness of the walls 2711 that the slot will produce a bending of a single wall 27a and, thus, will hold one of the cover members 2a closed while the other is opened.

A further advantage of the skewed slot 21a is that the slot can be made wider While still obtaining sufiicient frictional engagement with the walls 27a. The wider slot can accommodate variations in the thicknesses of the inserted edge portions of the walls 27a, that is, a grip can be obtained on walls thinner than the width of the slot, while walls thicker than the average can be inserted into the slot 21a without breaking the jaw-like free ends of the posts 17a.

As in the embodiment of FIGS. 1-5, the uppermost surfaces 18a of the cover-supporting posts 16a are substantially in the planar top surface 7 of the base member 1a. With the top of the posts 16a at the planar top surface 7, the point on the surface 19 contacted by an egg in a pocket 8 is disposed below the uppermost surface 18a and, thus, by avoiding the relative rigidity of reinforcement of the surface 19 afforded by the surface 180, is disposed at a relatively yieldable point on the surface 19. At the same time, the posts 16a are each provided with a slot 33 extending inwardly from the surface 18a. The bottom of the slot 33 is disposed substantially at the level of the top surface 711 of the base member 1a. The slots 33 which receive the edge portions of the free side walls 270, serve to prevent the edges of the free walls 27:: from deflecting laterally under the stress of a top load on the carton and thus from sliding off the posts. The slot 33 may be wide relative to the thickness of the edge portions of the walls 27a received therein and is shallow so that it may be readily thermoformed with the desired thickness and strength at the cover-supporting surfaces 131;.

In the closed position of the carton, that is, with the covers 2a in the position illustrated by dotted lines in FIG. 7, the free walls 27a of the cover members 2a rest at their ends on the upper edges 32 of the end walls 5a of the base member 1a and at intermediate points on the cover-supporting surfaces 18b of the posts 17a. The top walls 25 of the cover members 2a are thus supported by the walls 27a on edge. The cover-supporting surfaces 18b are preferably at substantially the level of the top surface 7a of the base member, and as in the embodiment of FIG. 1-5, the slots 21a are preferably slightly deeper than the level of the cover-supporting surfaces 18b. However, it will be apparent that, because of the inherent softness and flexibility of the material, some variations in this preferred design can be accommodated, for example, the bottom of the slot 21a may be substantially at the top surface 7a, as shown in FIG. 7.

The transverse rigidity of the carton may, if desired, be increased for example by reducing the longitudinal partition 9 between one of the cover-retaining posts 17 and one of the cover-supporting posts 16 to a transverse web or bridge extending between the respective transverse pair of egg pockets 8, the bottom of the Web or bridge being extended toward or to the bottom plane 6 of the base member 1.

What I claim and desire to protect by Letters Patent is:

1. An egg carton comprising a tray-like base member with an open top defining a top surface and having a longitudinal partition along the center line thereof and a plurality of transverse partitions dividing the same into two longitudinal rows of egg-receiving pockets, a plurality of posts disposed at the intersection of the longitudinal partition with the transverse partitions, said posts including one or more cover-retaining posts and coversupporting posts, each of said cover-retaining posts extending above said top surface and having a slot extending inwardly from the free end thereof through that portion thereof above said top surface and being disposed with the center thereof substantially in a plane normal to the top surface and along the longitudinal center line of the base member, each of said cover-supporting posts having a cover-supporting surface that is disposed substantially in the top surface, and a cover member hinged in the top surface along one edge to a longitudinal edge of said base member and adapted to be swung about said hinge between an open and a closed position relative to the open top of the base member, said cover member having a top wall that is disposed in spaced substantially parallel relation to the top surface when the cover member is in the closed position and having a free side wall disposed on edge on the cover-supporting surface of each of the cover-supporting posts and with portions thereof received within the slot of each of the cover-retaining posts for holding the same in the closed position.

2. An egg carton in accordance with claim 1 in which there is provided a second cover member similar to said first mentioned cover member and hinged to the other of the longitudinal edges of the base member, whereby the free side wall of both said cover members are disposed on edge on the cover-supporting surface of each of said cover-supporting posts and edge portions thereof are received within the slot of each of said cover-retaining posts.

3. An egg carton comprising a tray-like base member with an open top and with longitudinal and transverse partition means dividing the same into a plurality of longitudinal rows of egg-receiving pockets, a pair of cover members each having a top wall and a pair of longitudinally extending side walls depending from the longitudinal edges of said top wall, the free edges of the side walls of said cover members being hinged respectively to the upper longitudinal edges of said base member for swinging said cover members between an open and a closed position relative to the open top of said base member, said base member having cover-supporting means cooperating with the free edges of the other of said side walls of said cover members when said side walls are in closed position for supporting the top walls of said cover members in spaced relation to the open top of the base member, and at least one cover-retaining post at one of the intersections between said longitudinal and transverse partition means, said post having a slot extending generally longitudinally of the base member for receiving and holding the free edge of each of said other of said side walls of said cover members, said slot extending downwardly into said post to a bottom which is at least at the level of said cover supporting means whereby a load on said cover members is imposed primarily by said other of said side walls of said cover members onto said coversupporting means.

4. An egg carton in accordance with claim 3 in which said cover supporting means includes at least one coversupporting post at one of the intersections between said longitudinal and transverse partition means.

5. An egg carton in accordance with claim 4 in which the cover-supporting surface comprises the bottom of a longitudinal slot in the top of said cover supporting post.

6. An egg carton in accordance with claim 4 in which there are a plurality of cover-retaining posts and coversupporting posts disposed in alternating relation along the successive intersections between said longitudinal and transverse partition means.

7. An egg carton in accordance with claim 6 in which said cover supporting means also include flanges formed upon the end walls of said base member.

8. An egg carton in accordance with claim 3 in which the slot in said cover-retaining post is disposed at an angle of about live to fifteen degrees to the longitudinal center line of said base member.

9. A method of forming an egg carton with stack height gauging surfaces and having a tray-like base member with a top plane, a cover member hinged along one edge to the base member on a line in the top plane and a pair of cover-retaining posts extending above the top plane and adapted to cooperate with the cover to hold the same in its closed position, said method comprising holding a sheet of foamed plastic in a frame and heating the same to forming temperature, partially engaging the sheet with a female mold having the portion thereof corresponding to the top plane of the base member disposed horizontally and the portions thereof for forming the base member and the cover member disposed beneath the top plane of the base member and having mold sections for forming the cover-retaining posts extending above the top plane of the base member, pausing with the sheet disposed substantially at the top plane portion of the mold and with the post-forming mold sections extending into the sheet and causing the sheet to sag along a line between the post-forming mold sections to provide a doubled and adhered portion of the sheet along the line, bringing the female mold and the sheet into the forming position and engaging the same with a male mold to form the sheet and to reduce the doubled and adhered portion thereof to an upper and lower edge that are spaced apart a distance equal to the desired stack hei ht, permitting said sheet to cool to setting temperature, opening the mold and removing the sheet and trimming the completed egg carton there from.

lit. An egg carton of foamed plastic comprising a tray-like base member with an open top in a top plane and having a plurality of partitions including a longitudinal partition having an upper ed e disposed beneath said top plane and dividing the base member into a plurality of eg -receiving pockets arranged in longitudinal rows, a pair of complemental cover members each of which is hinged along one side to one side of the base member for swinging between an open position and a closed position with respect to the open top of the base memher, and at least one post disposed on the longitudinal partition and extending above the top plane for cooperating with said cover members in the closed position for locating the same, said carton being adapted to be nested relative to other cartons to provide a nested stack thereof, and means for determining the stack height beween adjacent nested cartons and for de-nesting the same comprising a thickened section between the upper edge of said longitudinal partition and the lower edge thereof in the direction normal to the top plane of said base member and disposed at the side of said post, said thickened section having a dimension corresponding to the desired stack height and comprising a doubled and adhered thickness of foamed plastic material, and means aligned endwise of said longitudinal partition for cooperating With a de-nesting device.

11. An egg carton of foamed plastic in accordance with claim 10 having a plurality of posts disposed in spaced relation along the longitudinal partition and including two cover-retaining posts extending above the top plane and cooperating with said cover members in the closed position for holding the same in the closed position and a cover-supporting post having an upper surface disposed substantially in the top plane of the base member and upon which the edges of the :cover members are adapted to seat in the closed position, said thickened section being disposed between said coverretaining posts.

12. An egg carton in accordance with claim 11 in which said means for cooperating with said tie-nesting device of the base member.

9 comprises a flange disposed substantially in the top plane 3,120,901 3,184,133 3,191,844 References Cited 3,243,096 UNITED STATES PATENTS 5 4/1953 Schwertferger 2292.5 X 45 657 8/1961 Emery 2292.5 X

6/1963 Brickner 2292.5

10 Boyd 229-25 X Boyd et a1 2292.5 Comstock 229-25 Crabtree 229-25 Great Britain.

DAVID M. BOCKENEK, Primary Examiner. 

